In the use of burning machines, means for proper and efficient disposal of the swarf or waste material produced is required. The usual practice has been to provide, beneath the burning table, a water table or tank into which the swarf falls. Thereafter, the swarf is emptied from the table, usually into a suitable drain or floor duct. To insure that the maximum amount of swarf reaches the water in the tank and does not pollute the surrounding environment and to protect the bars of the burning table, it is desirable to bring the level of the water to the top of the burning bars of the burning table and as close as possible to a workpiece extended across the bars for cutting. However, it is also sometimes necessary to lower the water level below the burning bars to permit inspection of the burning table, to allow workmen to remove a workpiece or scrap or for other similar purposes. In addition, it is essential that the means provided for removing the swarf or waste material from the burning table and the water table be quickly, efficiently and economically operated.
It is known that the water level in a container can be changed by introducing an amount of air sufficient to displace the water to the extent desired. This principle is sometimes referred to as "air over water". It has been employed in prior water tables, for example, in those described in U.S. Pat. No. 3,743,260 and in a design of Hyster Company reported in the April 1975 issue of Welding Design and Fabrication, pp. 106-7. It has not been used previously, however, in a structure of the type disclosed and claimed herein which incorporates in a simple water table design many desirable features including improved access to the burning table and ease and improved efficiency of collection of swarf or waste material.